The present invention relates to an optical fiber connector, and more particularly to the structure of a ferrule of an optical fiber connector.
An optical fiber connector is a device used in almost every optical communication device or other optical equipment, and is provided for coupling two optical fibers or an optical fiber with a light-emitting or light-receiving device or the like.
An example of a conventional optical fiber connector is described, for example, in Japanese Patent Laid-open Publication No. Hei-2-253207. FIG. 4 shows an optical fiber connector of this type which comprises a ferrule 2 made of ceramic, and a sleeve member 3 made of stainless steel supporting and securing the rear part of the ferrule 2 at the front bore 3A of the sleeve member 3. The ferrule 2 receives within a central orifice thereof an optical fiber 1 composed of a core and a clad layer.
It is necessary to manufacture the ferrule 2 depicted in FIG. 4 out of a stiff material, e.g. ceramic as in the case of the publication above mentioned, and it is not practical to manufacture the ferrule out of a cheep and brittle glass material, since the glass ferrule would be split by even a moderate external force, causing disconnection of the optical fiber 1. Consequently, an optical fiber connector of this type is expensive due to the expensive material for the ferrule.
Besides, to manufacture the ferrule 2 shown in FIG. 4, it is necessary to grind the outer surface of the ferrule with good accuracy. As shown in FIG. 5, such grinding is usually carried out with a grinding tool 10 the position of which is adjustable in the directions shown by arrows A, and co-operative supporting means 9 rotatably supporting the ferrule 2 at the both ends of the ferrule. The grinding of the work-piece is carried out one by one, so that the ferrule of this type is not adapted for mass production.
FIG. 6 shows another type of a conventional optical fiber connector in which a glass capillary tube 7 for receiving an optical fiber 1 is protected by a sleeve member 8 made of stainless steel. The sleeve member 8 entirely covers at the front part thereof the capillary tube 7 made of a brittle material, i.e. glass, thus avoiding the problem relating to a glass ferrule having the shape depicted in FIG. 4. The optical fiber connector shown in FIG. 6 is, however, also expensive due to the complicated structure of the sleeve member 8 receiving entirely the glass capillary tube 7 and holding the front end of the outer sheath 6 of the optical fiber cable. This structure is also necessary to grind the outer surface of the ferrule with good accuracy.